Time delay circuit breaker



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March 15, 1955 c. 'rHuMlM 2,704,311

TIME DELAY CIRCUIT BREAKER Filed March 9. 1950 9 ShetsSheet 1 5 4 56 7890 20 w MJUIOWMWIM 2da .im 400500K@ mfg@ March 15, 1955 c. THuMlM 2,704,311

TIME DELAY CIRCUIT BREAKER Filed Maron 9. 1950 9 Sheets-Sheet 2 IN VEN TOR. 644m EVM/ M March 15, 1955 c. THUMIM 2,704,311

TIME DELAY CIRCUIT BREAKER Filed March 9. 1950 9 Sheets-Sheet 3 0 Iv-Amlmlm BY MI5/4@ tomeyd March 15A, 1955 Filed March 9, 1950 c. THUMIM 2,704,311

TIME DELAY CIRCUIT"BREAKER 9 Sheets-Sheet 4 V/APENT /A/ AMPERES X100 za 3a 40 0 dovvwvloa 200 .aaa 4:70:00

Mardi l5, 1955 C- THUNHM v 2,704,311

TIME DELAY CIRCUIT BREAKER Filed Maron 9, 1950 9 Sheets-Sheet 5 I N V EN TOR. ha /aM/M LM/ew@ March 15, 1955 c. THUMIM TIME DELAY CIRCUIT BREAKER 9 Sheets-Sheet 6 Filed March 9. 1950 Illll Il llllll lli NWN.

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TIME DELAY CIRCUIT BREAKER Filed Maron 9. 1950 9 Sheets-Sheet 7 March 15, 1955 c. THUMIM TIME DELAY CIRCUIT BREAKER 9 Sheets-Sheet 8 Filed March 9. 1950 .1N VEN TOR. 'mez, 72h/NM1 Afro/Warn? March 15, 195.5 c. THUMIM TIME DELAY CIRCUIT BREAKER 9 Sheets-Sheet 9 Filed Maren 9. 1950 INN E .circuit currents.

United States Patent() TIME DELAY CIRCUIT BREAKER Carl Thumim, Yeadon, Pa., assignor to l-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application March 97, 1950, Serial No. 148,696

9 Claims. (Cl. 20G-108) The present invention relates to switchgear and more particularly to rcircuit breakers having `overcurrent trip units 'constructed so that a plurality of circuit breakers may be connected ina selective system, i. e., each of the circuit breakers is capable of interrupting any fault in its locality so that service is interrupted in only that part of the system where the fault occurs, leaving the remainder of the system in service.

An essential of circuit breakers for such selective system is the provision of a short time delay in the circuit breaker trip mechanisms responsive to short circuit currents, that is, currents approximately four tlmes normal and over, the short time delay belng of the order of cycles vin a 60 cycle system and being adjustable and individual ffor each circuit breaker, varying from `each yother by times measurable in cycles.

Some of the cIrcuIt breakers are also provIded with long time delays-f theorder of seconds for `operations in response to overcurrents vlt may valso be desirable to provide instantaneous trip operation ywith no intentional time delay in response to especially severe faults.

The problems raised in the construction and operation of circuit breakers `having multiple time delay characteristics for different current values have kbeen pointed out in Patent No. 2,439,165 and application Serial No. 488,841 filed May 28, 1943, now Patent No. 2,491,657 granted December 20, 1949 which are assigned to the assignee of the present invention.

Essentially the long time delay in the operation -ofthe trip devices for overcurrent conditions of lower values (up to, for instance, twelve ktimes normal) is adjusted to time of operation such that a circuit breaker trip unit will, on relatively low overcurrent conditions, be sufficiently delayed to permit the circuit breaker nearest to the load. in the selective trip 'system to remove the overloaded circuit to keep the number of circuits which may i beopened by such an overload to a minimum.

The long time delay feature, of course,'has the further function of providing temporary low overcurrent conditions with an opportunity to vclear themselves within a reasonable time before any' circuit *breakerV need open.

Thus the long time delay functions to permit only that circuit breaker to open which is necessary to clear an overload fault and the short time delay functions to permit only that circuit breaker which is necessary to clear a short circuit fault.

The application of the principle of selective tripping, i. e.,` the tripping of one of a plurality of circuit breakers connected in series between a vgenerator or source of power and the load in such Inanner that the particular circuit breaker nearest the fault opens before the other circuit breakers closer to the source of power can trip and thereby leaving them in operation becomes complex when an attempt is Vmade to apply the principle to short Here the permissible time delay is the order ofA cycles, from two to about thirty cycles and in some cases from two tolifteen cycles.

It will be apparent that, with such short time delays, securinga' sufficient and constant difference in time of operationv between the independent circuit breaker trip devices so that the one nearest the fault will trip, leaving the others in service,` is diicult.

In addition to the long and short time delays mentioned above, in order 'further to protectv not only the circuits' but' the circuitibreakers themselves, each circuit breaker in the selectivel system maybe provided with` a Fict:

quick trip feature free of any time delay adjusted to Ipermit an instantaneous trip of the circuit breaker at current values above .the current value for which the short .time `delay is set.

Thus, the long time delay of the trip operation, the short time delay of the trip operation, and the instantaneous trip each have their respective appropriate function depending on current conditions.

While the present invention is peculiarly adapted to therequirements of a selective system, the combination of .long time delay, short time delay and instantaneous trip may in appropriate circumstances adapt a single lcircuit breaker for use under specified load conditions where .these tripping characteristics are required for a Aparticular .piece of apparatus; that is, a particular machine may have characteristics duringr which a low overcurrent condition prevails for up to a few seconds and which usually .clears itself and it mayundergo other conditions where a high current condition kprevails for only a cycle'or two, and it may also require short circuit protection.

These various conditions would, of course, be Vmet by the long time delay, the short time delay and the instantaneous trip.

The primary object of the present invention is the provision of a novel combination tripping device for a circuit breaker having a long time delay, a .short time delay, and an instantaneous trip. j

Another object of Ithe `present invention is the provision of novel means for adjusting each of the longtime delay, the short time delay, and the instantaneous trip.

Another object of the present invention is the 'construction of a trip unit for a circuit breaker having` two armatures, one armature being provided with the long time delay and the instantaneous trip and the other .armature being provided with the short time delay'.

Another object of the present invention -is the provision of a novel short time delay unit for a circuit breaker tripping device.

Another object of the present invention is the provisionof a short time delay unit including an escapement mechanism wherein the resonant frequency of the verge of the escapement mechanism is damped out'.

It has'been found that in the utilization of an escapement mechanism as a time delay, especially for the-short time delay feature, that the curve of operation with ordinary escapement mechanisms was not a smooth one, time delay was not a proportional function of the fault current. y y

In accordanceiwith the present invention, it vhas been determined'that the observable error lay in the natural resonant frequency of the verge and the armature and `that means must be provided to overcome or nullify this natural resonant frequency in orderto obtain a smooth operation curve. v

It is'thus also an object of the present invention .to secure means on thek verge which will damp out its resonant frequency, such means either comprising loose kweights carried' by the verge or other means which will damp the natural frequency of. vibration of the verge so that the verge will move only in response tothe motion ofthe escapement mechanism and will in turn control' the escapement mechanism smoothly at all speeds of operatlon.

Likewise, means airey provided to damp out the resonant frequency of the short time delay' armature so that it will move-only in response to the magnetic force at' the vrate permitted by and in stepwith the escapementmechanism.

Another objectr of the present invention jis the provision of a novel dashpot construction for the longtime delay mechanism, the dashpot ybeing so arranged that a simple "adjustment of the dashpot housing will jprovide adjustment of the long time delay.

Another object of the present invention is the provision of a novel mens of Calibrating time delay so that a change of calibration of the long time delay 4 armature does not affect Ythe calibration ofv the short timey delay armature and vice versa.

Another' object of therpresent 'invention' is the" provision of novel eounteryt'feightirigV` means' so' 'that 'calibration is not affected by any change of position or inclination of the circuit breaker.

Another object of the present invention is the provision of novel means for changing from one short time calibration band to another. Another object of the present invention is the arrangement of a time delay mechanism so that all time delay is accomplished during approximately the first half or less of the armature stroke on both the short and long time delay. The armature, therefore, strikes the trip bar without any restraint and delivers with a hammer blow a maximum trip force.

Another object of the present invention is the construction of the armature and time delay mechanism, as well as of the calibration springs, so that the pull curve of the armature as it moves to trip closely follows above the pull curve of the calibration spring so that the device will reset if the current drops to normal load values at any position of the armature.

Another object of the present invention is the provision of short and long time delay elements as single selfcontained independently removable units.

Another object of the present invention is the arrangement of the time delay so that calibration of the overcurrent trip current value will not affect either time delay setting and vice versa.

The foregoing and many other objects of the invention will become apparent in the following description and drawings in which:

Figure 1 shows a series of curves for tripping time of the circuit breaker relative to the system current values.

Figure 1A is a View of a representative circuit breaker to which the time delay mechanism of the present insystem.

Figure 1C shows a series of curves indicating tripping time adjustments possible in accordance with my invention.

Figure 2 is a side View of the composite time delay device showing both the long and short time delays.

Figure 3 is a front view of the time delay mechanism.

Figure 4 is a side view partially broken away of the time delay mechanism taken from the opposite side from the view of Figure 2 and showing the long time delay element partially broken away.

Figure 5 is a vertical sectional view through the long time delay portion of the timing mechanism showing the armature in the de-energized condition and the dashpot set for maximum time delay.

Figure 6 is a view corresponding to that of Figure 5 vshowing the armature pulled to trip position.

Figure 7 is a view corresponding to that of Figure 5 showing the minimum time delay setting of the long time delay mechanism.

Figure 8 1s a view corresponding to that of Figure 6 ,showing the long time armature in the fully tripped position and the time delay piston after early release from its minimum timing stroke.

Figure 9 is a sectional view of the short time delay mechanism taken from line 9 9 of Figure l1.

Figure 10 is a view partly in section of the short time delay mechanism taken from line 10-10 of Figure 9.

Figure l1 is a view partly in section of the short time vtime delay mechanism taken from line 11-11 of Figure 9 Figure 12 is a side view of the run-off pinion and shaft of the time delay mechanism of Figure 9.

Figure 13 is a side view of the run-off gear assembly of the short time delay mechanism of Figure 9.

Figure 14 is a schematic view of the short time delay mechanism, its armature and trip bar showing one adjustment of the gear train.

Figure 15 is a schematic view corresponding to that of Figure 14 but showing a diiferent time delay setting of the gear train.

.1 8--18 of Figure 11 looking in the direction of thel arl' rows.

Figure 19 is a view in perspective, partially broken away, of the complete time delay apparatus.

Referring to Figure 1B, the source of power, which may be a generator, transformer battery, etc is connected to the main bus through circuit tbreaker A. The main bus is connected to several feeder busses through distribution circuit breaker B. Power is fed from this feeder bus to the Various loads such as appliances, motors, etc., through feeder breaker C. Each breaker has suicient interrupting capacity to handle all current (whether from source or from load as when a motor begins to act as a generator in case of a short circuit on the line) that can reach it. ln case of a fault or an overload, the overcurrent device trips the breaker and isolates the section on its load side before any other circuit breaker on its source side can open.

Figure 1 shows the time current settings for the three circuit breakers in juxtaposition so that behavior of each breaker under stress condition may be indicated.

Before entering into a detailed description of the novel circuit breaker of this invention, a brief description of the system and the requirements of the circuit breaker will be given.

In the curves, Figure l, the lower lines 1, 2 and 3 of each of the shaded sections 4, 5 and 6 indicate the maximum time allowable for continuation of any particular fault current and still achieve a restoration of the armature of the trip magnet to normal upon removal of the fault. lf the fault continues longer than this time, the armature will not restore but will go on through to trip the latch of its associated circuit breaker.

Thus, for example, assuming a fault of 20,000 am peres the armatures of the trip magnets for all three circuit breakers A, B and C of this system will start to move simultaneously. If the fault persists for approximately 0.92 second, which is the time at which 20,000 amperes intersects the curve 2 of circuit breaker B, the armature of circuit breaker B can no longer be restored to normal and will go through and trip the circuit breaker.

If, however, this particular fault is cleared at any time less than .092 second, then the armature of circuit breaker B which has moved through a predetermined angle in the interim will, however, restore itself to normal. As will be explained hereinafter, this will be true even if the current in the line drops from the fault current to a full load value for circuit breaker B.

The curves 7, S and 9 represent the maximum time for any particular fault current value at which the respective circuit breakers will extinguish the arc. Thus, again for example, if the fault current were 20,000 amperes, circuit breaker C will trip and attempt to extinguish the are in approximately .052 second, or less.

It will at once become apparent that curve 7 for circuit breaker C can have a time characteristic curve which is just immediately below the curve 2 of circuit breakver B.

This is true because the curve 7 represents the maximum time for the interruption of any particular fault for circuit breaker C. This maximum time must always be less than the maximum allowable time for any particular fault at which the armature of the next circuit breaker B will no longer be restored and selective tripping up to circuit breaker B will be lost.

inasmuch as the curve 7 represents the maximum allowed time for actual interruption of a fault current and the curve 2 represents the maximum time for which value the armature of the next largest circuit breaker will no longer be restored to normal, these two curves in actual practice may be spaced from each other in minimum measurable time. The actual spacing between shaded portions 4 and 5 is merely shown for convenience and could be substantially reduced.

summarizing the above, these curves illustrate the following: The pick-up, that is, the time at which the short @manager-1 ifi.; xlcurvel;fthen 'ithefarmature Ior* the trip=magnet -f'ofzrircuit breaker A only will restore etofnormal. `@Tlf :the fault-is f-cleared before Ethe time-'as representedA by` curve "2, "then I-thef armatures'of 'the circuitbreakersfA andB'Will reyfstoreyatldffnally, if forfany' reason the' fault -vclears 'beforegthe time of-curve l, then the armatures ofk trip magnets of vcircuit breakers 1A, Bv and'C will restore.

*"Should -the'l fault,zhowevenfeontinue -for atleast the time as'indicatedl-by curve` 1,f`=the-armature ofthe trip .mag-

net of circuit breaker C will,'go-"throngh'ato `vtripping y:actionirrespective of what happenstftothef'tfaultzcurrent thereafter. 'Correspondingly, 'if theffaultpersists longer "than -thetirne of curve-2, theytrip'devicesl lofboth A and 'QB will* be operated.

The curves ofy Figure lCgfshow adjustmentsy thatrniay -ibeemade` on the-armature of'anyone circuit breaker. 'Thus, for example, a circuit breaker may be set so that if `afault'current of-40;000l amperes ilowstorl a period of '.035 "second,l the armature offfthezcircuit breaker' C will ,ggolthrough and complete'the tripping operation. 'For any timeiofecurrent'ow `less than :035 second, however, fthe armature; ofcircuiti breaker C wouldbe restored to normal. 'The mechanism of the .circuit breaker "C .is

also set so that for all of the operations, including the movementy of'the armaturen'nresponseto the fault, the operation ofthe trip latch by the armature, the opening of the contacts of thecircuit breaker and the extinguishing ofthe karc all occur and are completed including the extinguishing ofthe .arc in .O'52,sec0nd.

Correspondingly, the .time Idelay ,mechanism of the circuit breaker C may be setsothat it willhavesthe characteristics as shown' by `the shaded` portions 11. Y ln the case of ,such `an adjustment, .ifthe fault current should tpersistvfor .O7 second, ,the armature :ofthe trip `magnet will nolonger restore and all ofthe operations ,described above, including the extinguishingoflthe arc, will -occur .alongiline 12 ,at ..12 second, and similarly the adjustment may be .madera occur iinr the shadedsectionjl as described above.

By further adjustment, moving .the curvesindividually lto Athe right so ,as [to changefthe pickrup timeffrom the jlxedvalue shownat -3500,amperes,each ofthe breakers may @be vset tohave individual' time such .as shown .ein

the curves of Figure l to provide selective tripping.

A simple adjustment, herein described,.which may read- `filybe made inthe .eld will .permit .arapid adjustment vof lthe circ-uit breaker so-that,the.short time. delai/curve will ;lie in any of the `three lbands. The .time delay itself may readily be adjusted either ,at VthefactoryV or Vinthe field. for variation ywithinnthelbands.

v,InFigureHL/kIliave shownva typical. circuit breaker to which-,the noveltrip .unitof ,the ,present invention may :beattachedrand in .connection with which it may be used, '.although itwill .be .apparent that any other well-known -`circuit breaker `design zmaybeused in .connection with y.the novelatimeudelay:mechanismwof the presenttinvenftion.

.Theci-rcuit breaker' .20. ofxFigure 1A. is mounted on Y.the insulatingwmolded element 21 which, in .turnris sup- .,ported against Vthe steel compartmentipanel212 Back upper connection stud 23 passes vvvthrough insulating molded element 21 and carries the circuit breaker main stationary contactl.

With circuit `breaker contacts in `closed position, current passes from the upper back connection stud23 to the main1stationary Contact .Zfl'rto the movable contact v.25Ontlie`movingcentact arm 26. When .the circuit breaker contacts-are opened to interrupt the currentow, `anarcis .drawn between `the -arcing horns Z7 and ZS vand. the .arc Visextinguished inthe arc chute 3?.

`With circuit breaker contacts inthe closed position,

current passes from .the moving contactZS throughthe lcontact arm 26 through lthe-pigtail 32 .to `terminal 33 of therseries trip coil 34. `Current ilowsthrough the trip coil 34, thence to terminal .-35 which is connected to theback connection stud 36 and thence back to the external V electric circuit.

The seriestrip `coil.`4,'energizes the .magnet titl of 'the trip deviceiwhich cooperates with 'the armatures 41 :andg42 hereinafter-described (and shown more clearly'in hFigure Zitotrip the :circuit breakeronthe occurrence ...oigan overcurrentorza fault .'conditioii. .Backrstopsfti and 45 are provided for limiting the baekpositionof -:'.thef'arrnatures.

the corresponding adjustable striking screws 44 or Ev'4S engage on the tripper bar 'leverl 47"to rotate `=theftripper vbar shaft 48 (Figures llt-17) inthe circuit breakerl'op'en ating mechanism dato trip the circuit' breaker.

The operatingmechanism`49fis connected byA linkage 5@ to the contact armSS' and may be operated' remotely Aby velectrical or pneumatic means or'by th'e'manual operating handleSl.

"nFigurel' I have shownfa side'-viewfcorresponii'ng gciieraly .e the view ofFigure l'AL-butwithsome'of the covering elements removed and illustratingthe-itime delay mechanism.

Varranged so Vth'atit` may attract either armature 5'41A'or `extending arm 7@ which engages the'endroll'er`f'71i0f lever 72 of the short time delay', geared mechanism`-73 `hereinafter described.

Armature i2 vwhich is operablepunderthe controlof .the long time delayniechanism in'responsento overcurrent fault conditions .is provided witha lug""75`vvhich'-is .connected by pin 76 to .the pull rod`77which in turn vis connected through a spring'to the longtime delay `mechanism titl. Armature @Zmay bendesigned to jpreve'nt chattering or. alternating current humqby :theweight $1 mounted .on spring 52 (lFiguresSL and "6) `.for the ypurposes and as disclosedY in application Serial. .No....68,83`1,

; led Ianuary.3,.1949, now UgSjPatent' 2,585,600,1granted February l2, 1952.

vThe instantaneous' trip and .the long time .d'elay' unit wili be described tirst in connection Iwith FiguresZ to-8. riheshort time delay unit Willbe hereinafterdescribed. As .abovejpointedrouu armature 42 is connected by pin "7e .to the pull rod 77. Pull'rod 77 extends .down

.into the :spring housing SS'throu'gh the vhole iirfthe top piece 86. A. compression spring 87 isrunder compressionbetween .top piecei of .the spring housing 35 and adjusting nut 9@ vof `the.rod. `Compression spring V87 is so adjusted that it is incompressible for currents below the desired setting of the instantaneous tr-ip, *and therefore is in effect a relatively` solid connection vbetween jpin '76 and the long time delay-mechanism Sit-below .for

electromagnetic forces exerted on-armature-.42 by the trip .magnet (40) energized by .current 'values iinthe .series coil'up to theinstantaneous'trippoint.

Spring 87 is,,however,compressibleWhere the'forces von the armature i2 correspond to current values at which instantaneous trip or" the circuit breaker latch V.mechanism is desired, in which case armature 42.is..moved under electromagnetic forces suicient toconipress.. spring A8'? to trip the circuit breaker latch .mechanism 49 .without any intentional timedelay.

When instantaneous ,trip is `not required, Athe..exten's`ible coupling comprised of housing Szand compression. spring i7 may be replaced .by solidQlirik connectingmembers 76 and 92. These solidconnecting rnemberswouldvnot change vin lengthy for any value ofV current. and .therefore the armature l2 would be` restrained rvatall times .bythe long time mechanism'l.

- Thus, the single armature 42 is used toiobta'infa -long time delay trip at currents .abovenormalin ythe-overload .range and an instantaneous.non-time delayttrip atrshort circuit currents or `othenerxtrernely 'high l'currents .-for 'which' the unit is set.

The lower end of .formed bracket-piece is conynected by pin 92 to the lever-93, pivotally mounted :on vpin carried bythe upper section S96 of" theflo'ngftirne '80. Lever 93 is rigidly keyed to the pin 95 so Vthatthe pin 95 rotates with lever 93. Crank -arm liis 'also keyed to the kpin 95at'its'otherend.

The .freely rotatable fend of crank 'arm :100 'iis Ifenn- .nected .by 'pin`101 to'piston.'rod.-102,'the opposite Lend v'of which is connected by pin 103 to piston 104 in the lllower housing section 105 of the time delay mechanism 80.

The two composite housing elements 96 and 105 may be manually adjusted up and down as required to vary the long time delay while permitting the elementsI 104. 103, 102, 101, 100, 95, 93, 85 and 42 to remain in the initial positions of Figures and 7.

In other words, in the time delay adjustment hereinafter described, the piston 104 remains stationary in the process of adjusting the long time delay and the two vcomposite housing elements 86 and 105 are moved up 125. Screw 123 may be rotated by turning the insulated knurled head 127 which will cause the nut 122 to move up and down vertically in accordance with the direction of rotation of the knurled head 127. The vertical movement of the nut 122 serves to increase or decrease the tension of spring 120 The long time delay mechanism 80 in housing 96 and 105 may be set independently of the setting of the calibrating spring 120 so that irrespective of any change in the setting of Calibrating spring 120, the physical position of the long time delay mechanism 30 in housing 96 and 105 will remain the same.

The piston 104 rides in the oil-filled chamber 130 in the lower housing 105 of the long time delay mechanism 80. The oil-filled chamber has several axial grooves 131 extending part of the length of cylinder 132, and is also provided with an annular lower recess 133. The piston 104 is a close sliding t within the cylinder 132 as seen in Figure 5.

When the armature 42 is attracted by magnet 4t), the armature 42 pulls extensible coupling element 85, which in turn draws up piston rod 102 and the piston 194 from the position of Figure 5 to the position of Figure 6.

Oil in the lower dashpot housing 105 of the long time delay mechanism 80 passes through the restricted opening 140 in the piston 104 and through the space between the piston 104 and cylinder 132 from the upper side to the lower side of the piston, thereby permitting the piston and the armature to move un at a speed determined by the rapidity with which the oil can flow through these openings,

When the lower edge of the timing surface of the Diston 104 reaches the lower edges of the axial grooves 131, then a more abundant oil flow is established through these grooves 131 from the top side to the lower side of piston 104, and the piston will now move more rapidly due to a decrease in the retarding element of the restricted oil movement. The armature 42 in turn will be permitted to move more ranidlv in its stroke to trip the circuit breaker latch mechanism 49.

This occurs as may readily be seen from a comparison of Figures 5 and 6 at about half or less than half the travel of the armature 42 from the initial position of Figure 5 to the fully sealed trio position of Figure 6, thereby permittingy the armature 42 to strike a hammer blow on the tripping bar extension 47 for tripping.

In other words, the full time delay occurs during only the rst half of the movement of the armature 42. ln order to calibrate the magnitude of the time delay, the housing 96 and 105 of the long time delav mechanism is arranged so that it may be bodily raised or lowered. The initial open position of the armature 42 is estabf lished bv an adjustment of the rubber tin adiustinr` screw 45 which provides an adjustable stop for the fully open position of the armature 42 by engaging with armature tie bar piece 63. In this open position the piston 104 is free to hang in space by being suspended from armature 42 through linkages, etc.

Consequently, the present invention contemplates that in order to increase or decrease the time delay, the dashpot housing elements 96 and 195 of the long time delay mechanism 80 be raised or lowered in order to increase or decrease the amount of stroke which the piston 104 must complete before its lower edge of its timing surface passes the lower edges of axial grooves 131 in the piston cylinder.

Accordingly, Figures 5 and 6 show the setting of the dashpot housing 96 and 105 of the long time delay mechanism 80 with a maximum time delay setting. The dashpot housing 96 and 10S of the long time delay mechanism 80 has been raised to a point where the piston 104 in Figure 5 must travel through its maximum stroke before, as seen in Figure 6, its lower edge of its surface uncovers the grooves 131.

When the dashpot housing 96 and 105 of the long time delay mechanism 80 is lowered as seen in Figure 7, then the distance that the piston 104 must travel from the fully open position of the armature of Figure 7 to a position where it uncovers the grooves 131 is reduced and consequently the total timing stroke is shortened.

As will now be clear, this adjustment of the time delay by raising or lowering the housing 96 and 105 of the long time delay mechanism 80 changes the time delay but does not affect in any way the minimum operating current value of the armature 42 so that the pick-up value of the armature 42 or of the value at which the armature will tend to operate remains the same value irrespective of the long time delay setting achieved by the upv/ard or downward movement of the dashpot housing elements 96 and 105 of the long time delay mechanism S0.

The dashpot housing elements 96 and 105 is supported slidably vertically in support bracket but is not rotatable with respect thereto. The lower end of the eX- terior of the dashpot housing 105 of the long time delay mechanism 80 is threaded on its side surface 152 and a ring nut 153 is placed thereover.

The ring nut 153 is locked in position by one or more machine screws 65 (Figure 4) so that it cannot accidentally be turned. These machine screws 65 are secured to the support bracket 150.

When it is desired to adjust the vertical position of the dashpot housing 96-105 of the long time delay mechanism Si) with relationship with support bracket 150, the ring nut 153 (Figure 7) is released by removal of the machine screws 65 as above described and the nut 153 is turned on the threaded' section 152 of the lower housing element 105 of the long time delay mechanism 80.

After the ring nut 153 has been turned to the desired position, it is secured once more against the support bracket 150, thereby determining the vertical position of the dashpot housing elements 96--105 of the long time delay mechanism 80.

Obviously, when the ring nut 153 is turned to raise dashpot housing 96-105 to its highest position, as seen in Figure 5, then the maximum time delay will result because of the greater stroke of the piston before it clears the axial grooves 131 in cylinder 132. When it is turned to lower the dashpot housing 96-105 as seen in Figure 7, then a diminished time delay will result .because of the reduction in the stroke of the piston 104 before it clears the axial grooves 131 of cylinder 132.

The type of time delay provided by the long time delay has already been described in connection with the graphic illustration of Figure l and corresponds to curve sections A, B and C.

The short time delay is indicated in Figures 1A and 2 and is more specifically disclosed in Figures 9 to 16, inelusive.

Basically, the short time delay member 73 is a mechanical escapement mechanism having a verge which controis the speed of rotation of the lever 72. Lever 72 bears against the lower extension 70 of the short time armature 41 so that when the short time armature 41 moves from the full open position of Figures 14 and l5 toward the tripping position of Figure 16 and before it completes its full trip movement of Figure 17, it must rotate the lever 72 in a clockwise direction as the armature rotates in a counterclockwise direction.

Since the armature 41 cannot rotate toward tripping position without rotating the lever 72 in a clockwise direction, the escapement mechanism in the short time delay housing 73 which is secured to the lever 72 controls the speed of rotation of said lever 72; therefore the escapement mechanism 73 controls the speed of movement of the armature 41 in its stroke toward the trip position of the device.

The escapement mechanism 73, as seen more particu- 161 and shrouding plate 162 thereon (see also Figure 13).

Segment gear 161me shes ywith the pinion 172. The pinion 1721s provided witha recess"1'64(see also Figure 12,) registering with the shrouding plate162.

Asthe shaft160 is turned, lthe Segment gear 161 which ...meshes .with the-.piniOnj172 rotates the pinionuntil the segment gear A 161 escapes j fromthe pinion 172. Y,The

.shrouding plate1'62 is recessedat'j166 belowthe level of the teetht-167 ofthe segment gearj161 so that it does not interfere with themeshing engagement between teeth 167 of segmentgearlland the teeth ofipinion 172.

After jtheu fulltime delay; has b eenachieved as hereinafter described, Ithenjit is neess'ary that the armature escape the ytime delay mechanism. At this time the shrouding plate 162 and particularlyportion 168 thereof comes intoregistry with the recess.r1'64 of the pinion 172 hold- Ving the pinion.172stationarywhile'the s hrouding plate 162 ,andthe shaft 16may rotate .Lealdly with respect thereto.

.The segmentgear 1j61' is cutaway atl 173 so that it will not -obstructkthe movement of .segment gear 161 and shaft .160;at this run-oiposition.

Consequently, themovementof teeth'167 of the seg- Vment .ge'arfrom theposition of Figures 14 orvlS to the position of Figure 16 is ltime delayed thereby delaying the rotation of lever 72 and resulting in a time delay on .armature ,41, but when thearmature reachesthe half-way :point as shown in Figure. 1 6, then as ycan' be seen from a AComparison ofFigures-l6 and 17, thesegment gear 161 disengages tooth. engagement with the. pinion 172 permitting an unrestrained strolreof v.the armalture '141 to engagementwithtripper bar 47 v.with ahamrner blow.

"'In order to avoid misalignmentbetween the parts of 4`the escapement mechanisnngthe `engagement of the raised -porton1168 of the shrouding plate162in the recess 164 .of `thepinionV 172 holds the"pinion. 17 2 and `the associated mechanism hereinafter described yin .the position they held at the time the. teeth 167 .of gear segment 161 left the ,pinionf172 so that during the returnnmovement when the Ateethv 167 engage the pinion 1' 7 2,the relationshipy between the teethl'l; the; raised portionr168 -of shrouding plate -162and the recess 164 of pinion 172 .will remain in the desired condition, `to ire-establish -mesh engagement of the teeth of thesegment gear 161,and the teeth of the .pinion `gear. 172.

Thus, rin order to .achieve.the short time delay, it is necessary to selectively delaythe rotation of the pinion .172. Pinion 172 Vis .carried on 'shaft 175. which 'carries the-gear 176.

. Gear 176meshes with gear 177 on shaft 178which carries the gear 179. Gear 179 meshes with gear 1 80 on shaft 181 whichcarriesthe ,toothed escapement rack 182'.

Verge 190 rotatable kongpin.. 191 has opposite vteeth 192, 1 93.which alternatively engagewith the. .teeth .ofv escape- -ment wheel182 and limit itss'peed of rotation ,by the speed with'whichthe teeth 192arid 193 ofthe `vergellib can k successively escapef-thecwheelllSZ by oscillation of the verge 190. kThe planes. .ofthey teeth of the escapement wheel1182 areso oriented that thedirection of theforce linek between .Wheel182 and vergey teeth .192 falls outside of verge pivot191 by a Ydefinite Aamount. The resulting vmovementcauses the speed'of oscillationof verge 190 to vary in direct `proportion to the magnitude of the kforce impressed on it by wheel 182.

Thus, as--has been pointed `out,.the rotation of armature 41 to the trip position causes .itsend 76 to rotate the operating lever 72 ofthe short time mechanism'73 which -support and may be rotatably adjusted-.as shown, .for instance, by a comparison ofFigures 14 and` 15 to .a position where a greater or less number of the teeth 167 -of lthe gear segment 161 mustpass lin engagement with the -pinion 17f2 before the run-oif condition isachieved whereinl extension 1 68 of theshroudingV plate 162'passes :freely throughv the recess 16.4-ofthepiniorr 172 whilethe-recess 10 173 ingear segment 161 permits-free rotationv` of the gear segment-161 past the pinion-172. 7

Thus, in the adjustmentof Figure 14, the timedelayis relatively greater than in the yadjustment of Figure 15 Where fewer teeth of gear segment161 must traverse the pinion 172 before the run-od condition whichpermits'the armature to move freelyas shown in Figure 17 is reached. This adjustment is utilizedfto obtain a Vernier-adjustment of the short time ldelay mechanism 73 withinv a ygiven time delay band.

YThe time delay maybe adjusted for the three xbands previously described in connection with Figure lby-an adjustment of the eifective lengthof lever 72.

Thus, lever 72 may beprovided with ythree securing holes`72a, 72b, 72C for securing the same to the shaft 160. Where the lever 72 is of lits minimum adjustable. length, kthen the armature41 Vfor a given current valueexertsless torque about the shaft'lt) torotate the geared mechanism 73 and the time'deiayris maximum. 'Where'lever 72 is made relatively longer, the armature 41 exerts more torque about shaftV 161) due4 to increased eective lever length and the `time delay is relatively less.

By providing three selectively usable securing .holes 72a, 72b, 72con the lever-72 for securing the same by means of screw22 .to the shaft 160, a time delay adjustment to set the short time delayA for each of the three bands previously described inv Figure l may be obtained.

VvThe short time ydelayarmature 41 is used for the purpose of obtaininga shorttime delay expressed in cycles "for currents exceeding a given minimum value. 'This is in contrast vto the. long time ,delay armature 42 which is used for thepurposeof obtaining along time delay expressed inseconds voryin;minutesjfor current values in `vthe Vrecognized rangeof overcurrents and also for the-purpose of obtaining anu instantaneous trip which operates faster than the longtime delayas previously describedin the event of a vshort; circuit or other predeterminedA high overcurrerit condition.

`The short `time delay armature `41 is adjustably calilbrated,as.to its pick-up point by the calibrating spring'230 (Figure 2 and Figures. 14to 17). Spring 230 is connected to opening2111 on'jthe armature and to Calibrating nut 2.32. on the calibratingscrew 233 which may be readily rotated in order to move thevnut 232 up or down'thejindicator scale 235 which .may be used, if desired.

`Raising the n ut 232 will .decreaserthe tension of the restraining spring 230 kand lowering nut'232 will increase the tensionof the restraining spring. Thus, the short time delay armature 41 may be adjusted to pick up atany .desired value of current.

It will be obvious that the adjustment of the short time rdelay mechanism 73 is completely` independent of the adjustment .of the ealibratingvspring 230 so that irrespective of the setting ofthe calibrating springZS and the indicator nut 232, the Vtime current AVcharacteristics will remain as set and the spring23il calibration may be altered without altering the time current characteristics for any given percentpcurrent `in eXCess of the minimum pick-up value .of armature 41.

' ly `this means, therefore, la Asimplified ,independently adjustable long time delay mechanism, arsimplited in- Qdependently,adjustablejshort time delay mechanism, and

a simplified independently adjustable calibrating means for each .offthve armaturesv is provided.

Thus, acircuitvbreakermay be set for appropriate time delays at the factory andfthereafter a eld setting of rthe `pick-up value of either orboth of the armatures will not affect the *timel delay characteristics and the timedelay Vsettings may each ,independently be adjusted in the field and thereafter the pick-up value or calibration ofthe armatures ymay be. variedin the eld Without interfering with thetirne delay settings or Lthe relative values at which each of the time delay factors will occur. The change in the :minimum pick-up of .the vinstantaneous element due to change in the long time delay spring will. vbe

- negligible.

higher level lis that the curve for one armature wouldbe displaced to the right-without interfering with the operation ofthe circuit breakers in accordance with the curve for :the l other armature.

The entire time delay apparatus s shown in perspec- Ative in Figure 19; the description of the parts in connection with the other fragmentary and diagrammatic figures will now make the complete operation clear.

In the operation of the short time delay unit herein described in connection with Figures 9 to 16, it was found at first that the curve at certain values did not follow the desired path but that the time delay characteristics varied somewhat from the optimum. The intermittent motion caused by the escapement type of timing was transferred in the form of a forced vibration to armature 41 and caused natural frequency vibration of 4l result ing in lack of timing accuracy. This was cured by the elastic suspension of the counterweight 8in of Figure 2 on a pair of rubber washers 81d inserted between the plates of the armature thereby acting as a damper or by the vibrating mounting of weight 81 on spring 82 of Figure 5. Both of these were preferable to the soiid mounting of counterweight 81e of Figure 4. Member 31 may be either a solid member, a vibrator as in Figure 5, or a cushioned member as in Figure 2. It was also found that the natural resonant frequency of the Verge 190 asserted itself at certain speeds of the rack 182 and periods of oscillation of the verge 19t) in relation to the pulsations of the forces due to the alternating current magnetic 'forces so as to cause the verge to effect synchronized action with the rack 132. An unproportional increase in the time delay will result if the elements of the device are allowed to reach this stage.

Accordingly, and to damp this natural frequency of the verge 19), a pair of holes 240 are placed in opposite sides of the verge 190 (see Figures 1l and 18) and loose rivets 241 are mounted therein, the rivets 241 shaking or rattling during the oscillation of the verge 19t) and damping out its natural frequency of vibration.

Various other means may be utilized to destroy the natural frequency of vibration of the verge 190 or the effect thereof, such as the use of liquids sealed in two chambers with a connecting orifice, or the use of spring members of various kinds, but the utilization of the loose rivets in the holes in the verge 19t) was found to smooth out the curve of operation so that the curve of operation followed the actual theoretically correct curve without any variation. This type of operation is the exact opposite of that required in a time piece in which the natural frequency of the oscillating member is depended upon to maintain time keeping accuracy and the greatest effort is made to prevent differences in tension of the actuating spring to affect the period of oscillation of the verge.

In the foregoing I have described my invention solely in connection with specific illustrative embodiments thereof. Since many variations and modifications of my invention will now be obvious to those skilled in the art, I prefer to be bound not by the specific disclosures herein contained but only by the appended claims.

I claim:

1. In a trip mechanism for a circuit breaker including current responsive means energizable in response to fault currents, an armature comprising a pair of plates for said current responsive means operable in response to the energization of said current responsive means, a trip device operable in response to the operation of said armature, an intermittently operable time delay mechanism connected to said armature for controlling the rate of operation of said armature, the intermittent motion of said time delay mechanism being reflectable in said armature, and means for damping out the natural resonant frequency of said time delay mechanism comprising a counter weight elastically suspended on a pair of rubber Washers inserted between said plates of said armature.

2. In a trip mechanism for a circuit breaker including current responsive means energizable in response to fault currents, an armature for said current responsive means operable in response to the energization of said current responsive means, a trip device operable in response to the operation of said armature, time delay mechanism connectible to said armature and comprising an escapement for controlling the rate of operation of said armature, the intermittent motion of said escapement being reflectable in said armature, means on said armature for damping out said vibrations produced by said intermittent motion, said means comprising a counter weight elastically suspended on a pair of rubber washers inserted between a pair of plates of said armature, the verge of said escapement having a natural resonant frequency, and loosely mounted rivets on said verge propellable radially for damping out the natural resonant frequency of said verge.

3. In a trip mechanism for a circuit breaker including current responsive means energizable in response to fault currents, an armature for said current responsive means operable in response to the energization of said current responsive means, a trip device operable in response to the operation of said armature, time delay mechanism comprising an escapement, said time delay mechanism being connected to said armature and controlling the rate of operation of said armature, the oscillations of said escapement being reflectable on said armature, cushlon= ing means on said armature for damping each refiected oscillation, the verge of said escapement having a natural resonant frequency, and means for damping out the natural resonant frequency of said verge, said damping means comprising a mass loosely coupled to said verge.

4. In a trip mechanism for a circuit breaker including current responsive means energizable in response to fault currents, an armature for said current responsive means operable in response to the energization of said current responsive means, a trip device operable in response to the operation of said armature, time delay mechanism comprising an escapement, said time delay mechanism being connected to said armature and controlling the rate of operation of said armature, the oscillations of said escapement being reiiectable on said armature, cushioning means on said armature for damping each reected oscillation, the verge of said escapement having a natural resonant frequency, and means for damping out the natural resonant frequency of said verge, said damping means comprising a plurality of masses loosely coupled to said verge.

5. In a trip mechanism for a circuit breaker including current responsive means energizable in response to fault currents, an armature for said current responsive means operable in response to the energization of said current responsive means, a trip device operable in response to the operation of said armature, time delay mechanism comprising an escapement, said time delay mechanism being connected to said armature and controlling the rate of operation of said armature, the oscillations of said escapement being refiectable on said armature, cushioning means on said armature for damping each reected oscillation, the verge of said escapement having a natural resonant frequency, and means for damping out the natural resonant frequency of said verge, said damping means comprising a plurality of openings in said verge spaced from the center of oscillation thereof and masses loosely mounted in said openings.

6. In a trip mechanism for a circuit breaker including current responsive means energizable in response to fault currents, an armature for said current responsive means operable in response to the energization of said current responsive means, a trip device operable in response to the operation of said armature, time delay mechanism comprising an escapement controlling the rate of operation of said armature, lever arms connecting said escapement to said armature, and means for changing the ratios of said lever arms to vary the amount of time delay of said escapement mechanism on said armature.

7. In a trip mechanism for a circuit breaker including current responsive means energizable in response to fault currents, an armature for said current responsive means operable in response to the energization of said current responsive means, a trip device operable in respouse to the operation of said armature, time delay mechanism comprising an escapement controlling the rate of operation of said armature, said escapement having a natural resonant frequency, means for damping out the natural resonant frequency of said escapement, lever arms connecting said escapement to said armature, and means for changing the ratios of said lever arms to vary the amount of time delay of said escapement mechanism on said armature.

8. In a trip mechanism for a circuit breaker including current responsive means energized in response to fault currents; an armature for said current responsive means; a trip device operable in response to the operation of said armature; a long time delay mechanism comprising a fluid displacement device; means connecting said armature to said fiuid displacement device; said means comprising a compression spring forming a portion of said connection from said armature to said uid disv placement device; an adjustment means for said compression spring to adjust the degree of 'compression of said spring without altering the length of the connection between said armature and said tluid displacement device; said adjustment means eiective to render said compression spring incompressible for current values below a predetermined value and thereby form a relatively solid connection between said armature and said fluid displacement device.

9. A time delay mechanism for a circuit breaker having a trip unit with a first and second armature; said time delay mechanism comprising a long time delay mechanism operable to delay the operation of said first armature of said trip unit for times of the order of seconds in response to an overload current and a short time delay mechanism operable to delay the operation of said second armature of said trip unit for times of the order of cycles in response to short circuit currents, said long time delay mechanism comprising a uid displacing member, said short time delay mechanism comprising an escapement, a common container for said long and short time delay mechanism, said container being removably securable to said circuit breaker, and means individual to. said long and short time delay mechanism for callbrating said mechanism individually and independent of any eiect on the other of said mechamsms.

References Cited in the le of this patent UNITED STATES PATENTS 1,014,257 Rosenqvist Jan. 9, 1912 2,195,041 Von Schlippe Mar. 26, 1940 2,352,048 Wallace lune 20, 1944 2,419,892 Graves, Jr. Apr. 29, 1947 2,439,165 Graves, Jr. Apr. 6, 1948 2,486,596 Graves, Ir. Nov. l, 1949 2,486,602 Jensen et al Nov. 1, 1949 2,486,613 Ridgley Nov. 1, 1949 2,495,127 Oppel Jan. 17, 1950 2,504,855 Ludwig et al Apr. 18, 1950 2,550,128 Taliaferro Apr. 24, 1951 2,570,170 Viti Oct. 2, 1951 2,632,823 Oppel Mar. 24, 1953 FOREIGN PATENTS 1,891 Great Britain Jan. 31, 1905 

